The present invention relates to a testing device, particularly a probing assembly for an electrical circuit board suitable for testing disconnection, short-circuiting, leakage or the like by means of contact with test terminals on the circuit board.
Examples of the testing devices of similar types are shown in FIG. 1 and FIG. 2. The example shown in FIG. 1 is similar to those shown in a catalogue of Shonan Enginering Company, a catalogue of Nippon Denshin Company, a catalogue of Seiken Company. The example shown in FIG. 2 is similar to those shown in a catalogue of Nippon Micronics Company, a catalogue of Kyowa Riken Company, a catalogue of Hugle Electronics Company.
The device of FIG. 1 comprises spring-loaded probe pins 1, leads 2 electrically connecting the probe pins 1 to an external measurement circuit, and an insulating board 3 for mounting the probe pins 1. The probe pins 1 are provided in number and pitch corresponding to test terminals 5 on an electrical circuit board 4 on which the test should be performed. Although only two probe pins 1 and two test terminals 5 are illustrated, there are usually a lot more of them. The probe pins 1 are aligned with the test terminals 5 and are pressed against the test terminals 5. This is done by movement of the board 3 or the board 4 toward the other. The spring built in the probe pins 1 serves to ensure good contact while avoiding excessive contact pressure. When the electrical connection between the probe pins 1 and the test terminal 5 are achieved, disconnection, short-circuiting, leak current or the like can be tested by means of the external measurement circuit connected via the leads 2.
The device of FIG. 2 comprises a tapered strip shaped probe pins 6, leads 7 for connecting the probe pins 6 to an external measurement circuit, an insulating board 8 for mounting the probe pins 6. The parts of the strip-shaped probe pins extending parallel to the circuit board 4 serves as a leaf spring to ensure good contact between the probe pins 6 and test terminals 5 on the board 4.
The devices shown in FIGS. 1 and 2 have limitations in that they cannot be formed to achieve simultaneous contact with a large number of test terminals 5 arranged at a short pitch. For instance a liquid crystal display panel may have 300 test terminals arranged at a pitch of 0.3 mm which must be contacted simultaneously for efficient testing. Moreover, the probe pins 1 and 6 of the devices shown in FIGS. 1 and 2 are made of metal and have sharp tips. When the sharp tips engage with the test terminals 5, the test terminals 5 may be damaged which may cause defects after the test (e.g., breakage or peel-off under heat).